mirror of
https://github.com/tesseract-ocr/tesseract.git
synced 2024-12-28 02:58:17 +08:00
94 lines
3.4 KiB
C++
94 lines
3.4 KiB
C++
// Copyright 2012 Google Inc. All Rights Reserved.
|
|
// Author: rays@google.com (Ray Smith)
|
|
///////////////////////////////////////////////////////////////////////
|
|
// File: doubleptr.h
|
|
// Description: Double-ended pointer that keeps pointing correctly even
|
|
// when reallocated or copied.
|
|
// Author: Ray Smith
|
|
// Created: Wed Mar 14 12:22:57 PDT 2012
|
|
//
|
|
// (C) Copyright 2012, Google Inc.
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
//
|
|
///////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef TESSERACT_CCUTIL_DOUBLEPTR_H_
|
|
#define TESSERACT_CCUTIL_DOUBLEPTR_H_
|
|
|
|
#include "errcode.h"
|
|
|
|
namespace tesseract {
|
|
|
|
// A smart pointer class that implements a double-ended pointer. Each end
|
|
// points to the other end. The copy constructor and operator= have MOVE
|
|
// semantics, meaning that the relationship with the other end moves to the
|
|
// destination of the copy, leaving the source unattached.
|
|
// For this reason both the copy constructor and the operator= take a non-const
|
|
// reference argument, and the const reference versions cannot be used.
|
|
// DoublePtr is useful to incorporate into structures that are part of a
|
|
// collection such as GenericVector or STL containers, where reallocs can
|
|
// relocate the members. DoublePtr is also useful in a GenericHeap, where it
|
|
// can correctly maintain the pointer to an element of the heap despite it
|
|
// getting moved around on the heap.
|
|
class DoublePtr {
|
|
public:
|
|
DoublePtr() : other_end_(nullptr) {}
|
|
// Copy constructor steals the partner off src and is therefore a non
|
|
// const reference arg.
|
|
// Copying a const DoublePtr generates a compiler error.
|
|
DoublePtr(DoublePtr& src) {
|
|
other_end_ = src.other_end_;
|
|
if (other_end_ != nullptr) {
|
|
other_end_->other_end_ = this;
|
|
src.other_end_ = nullptr;
|
|
}
|
|
}
|
|
// Operator= steals the partner off src, and therefore needs src to be a non-
|
|
// const reference.
|
|
// Assigning from a const DoublePtr generates a compiler error.
|
|
void operator=(DoublePtr& src) {
|
|
Disconnect();
|
|
other_end_ = src.other_end_;
|
|
if (other_end_ != nullptr) {
|
|
other_end_->other_end_ = this;
|
|
src.other_end_ = nullptr;
|
|
}
|
|
}
|
|
|
|
// Connects this and other, discarding any existing connections.
|
|
void Connect(DoublePtr* other) {
|
|
other->Disconnect();
|
|
Disconnect();
|
|
other->other_end_ = this;
|
|
other_end_ = other;
|
|
}
|
|
// Disconnects this and other, making OtherEnd() return nullptr for both.
|
|
void Disconnect() {
|
|
if (other_end_ != nullptr) {
|
|
other_end_->other_end_ = nullptr;
|
|
other_end_ = nullptr;
|
|
}
|
|
}
|
|
// Returns the pointer to the other end of the double pointer.
|
|
DoublePtr* OtherEnd() const {
|
|
return other_end_;
|
|
}
|
|
|
|
private:
|
|
// Pointer to the other end of the link. It is always true that either
|
|
// other_end_ == nullptr or other_end_->other_end_ == this.
|
|
DoublePtr* other_end_;
|
|
};
|
|
|
|
} // namespace tesseract.
|
|
|
|
#endif // THIRD_PARTY_TESSERACT_CCUTIL_DOUBLEPTR_H_
|